Processing tobacco



July 21, 1964 M s. BLOCK ETAL 3,141,462

PROCESSING TOBACCO Filed Sept. 22, 1961 H2O PLUS ADDITIVES FIG.I.

SOAKING AND MIXING TANK AIR F'NES SUPPLY LIQUID TANK RE'ruRN NO 'a's l320 P -3|' v HOMOGENIZER 2| 1 mxmc TANK' I 2'2 20 RECYCLE 23' EXCESS vHOMOGENIZER LAYER RETURN RELIEF STORAGE TANK vA| vE C 24 7 RECIRCULATINGJ 25 LINE 33 PUMP 26 a P 6!] INVENTORS:

JOSEPH J. LUBUS MELVIN D.SIDBURY M SABEL BLOCK CLIFFORD O.JENSENSEPARATOR VACUUM PUMP THEIR ATTORNEYS United States Patent 3,141,462PROCESSING TOBACCO M Sahel Block, Bloomfield, N.J., and Joseph J. Lubus,Melvin D. Sidbury, and Clifiord 0. Jensen, Greensboro, N.C., assignorsto P. Lorillard Company, New York, N.Y., a corporation of New JerseyFiled Sept. 22, 1961, Ser. No. 139,928 14 Claims. (Cl. 131-140) Thisinvention relates to the manufacture of tobacco products and it relatesparticularly to the manufacture of sheet tobacco from tobacco wasteproducts, such as, for example, tobacco leaf stems, slivers, leaffragments, tobacco dust and the like.

In recent years, so-called reconstituted tobacco has been manufacturedfrom the waste products of tobacco generally by either of two processes.One such process is essentially the same as that which is used in themanufacture of paper, wherein the tobacco particles in the form ofslivers, stern fragments, leaf fragments and tobacco dust are beateninto or disintegrated into a pulp in the presence of 40 to 50 parts ofwater to about one part by weight of the waste tobacco products. Theresulting highly fluid pulp'is discharged on to a paper-making wirewhere a large proportion of the moisture is removed and then theresulting sheet is dried with heat to provide a self-sustaining sheet oftobacco. Because a large amount of water is necessary in thepaper-making process, its removal is costly and renders this processuneconomical in current use.

The other process, while not requiring large quantities of water, isentirely dependent on binding materials to unit the finely-dividedtobacco particles into a sheet, since they are incapable of uniting andforming, by themselves, a continuous self-supporting sheet. For thatreason it has been necessary to admix with the fine tobacco particlessubstantial proportions of binders, for example, up to of suitablebinders such as, for example, carboxymethyl cellulose, vegetable gumsand the like, to render the resulting sheet self-sustaining. Althoughconsiderable research for non-toxic, tasteless and odorless binders hasbeen conducted, the known binders still impair the flavor of the tobaccowhen burned in a cigarette, cigar or pipe, and render it brittle anddark in color, so that only a small portion may be used in blends withthe natural leaf. Furthermore, the cost of the binders in the relativelylarge proportion required is relatively high, so that as in the case ofreconstituted tobacco made according to the paper-making process, thecost is higher than desirable for economical use of either process.

In accordance with the present invention an economical process isprovided for reforming tobacco Wastes into a generally useful tobaccoproduct, whereby the disadvantages of the prior processes are overcomeand a greatly improved tobacco product more nearly approaching thenatural leaf is obtained.

More particularly, the present invention provides a process whereintobacco waste particles such as stems and slivers are broken down orseparated into fibers of substantial length capable of forming aself-sustaining mat or felt, in which other tobacco fines, such asparticles broken from tobacco leaves during processing, may beintermingled and wetted with a relatively small quantity of water toform a thick slurry, which, after drying,

is self-sustaining even when completely devoid of binder. For example,the tobacco stem particles and tobacco slivers are mixed with water inthe proportion of about one part of stem fragments and slivers to 6 to13 parts by weight of water and this mixture is subjected to intensive.abrasion, vibration and impact which defibers the stems and slivers(separates the fibers in the stems and slivers) without breaking thefibers into short lengths.

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The fibers resulting from such a defibering operation may be as much asa quarter to a half an inch long and thus are capable of forming amatrix or felt of excellent strength and handling properties. To theaqueous mixture of fibers may be added other tobacco particles, such asNo. 8s, i.e., tobacco leaf fragments which pass through a No. 8 screen(8 meshes per square inch), including tobacco dust and the like, andthis material is subjected to further disintegration to form a mixtureof the long fibers and tiny particles in which the moisture content isabout six to eight times by weight of that of its solid content. Such amixture is in the form of a thick slurry which cannot flow or be pouredon to a paper-making wire or other surface in the form of a uniform thinlayer. In accordance with the invention, the slurry is deposited byspraying to produce a layer of a thickness corresponding approximatelyto the thickness of leaf tobacco. The layer may then be subjected to asqueezing operation which, aided by suction, removes excess water andmay then be dried in any suitable way, such as, for example, by means ofinfrared radiation, hot air or the like to produce a finished sheetwhich is highly flexible and has a good bulking density and handlingproperties so that it may be readily intermixed with cut cigarettetobacco or the like for producing cigarettes and other tobacco products.

A cigarette blend of high quality made of leaf tobacco has a specificvolume of 200 on an arbitrary scale used as a standard in the cigaretteindustry. The new material has a specific volume of 210 on that scale,showing that more cigarettes can be obtained from the same weight of thenew tobacco sheet than with an equal weight of cut leaf tobacco becauseof its lower density. By contrast, tobacco stems have a specific volumeof and reconstituted tobacco made by the paper-making process has aspecific volume of on the aforementioned standard scale.

The new product resulting from this invention has the light colorcharacteristic of natural tobacco leaf, a good flavor when smoked sinceit contains no added binder, and a self-sustaining burning power, evenin sheet form. It has about twice the sugar content of ordinaryreconstituted tobacco manufactured by paper-making process and it hashandling properties superior to natural leaf tobacco in cigarette-makingoperations where the material is subjected to cutting and processing inmachinery which has the tendency to break down the tobacco shreds.

For a better understanding of the present invention, reference may behad to the accompanying drawings in which:

FIGURE 1 is a schematic flow sheet illustrating a typimal methodembodying the present invention; and

FIGURE 2 is a schematic view in longitudinal section of a device forprocessing and disintegrating or defibering the tobacco products.

Referring now to FIGURE 1 of the drawing, tobacco stems and fragmentsthereof which may range in length up to several inches are fed into ahammer mill 10 where they are broken into relatively shorter lengths,e.g., about one-eighth to one-half inch, but not ground to powder. Theshorter stern particles, together with tobacco slivers, are transferredto a soaking and mixing tank 11 where water is added in the proportionof about 6 to 13 parts of Water to one part of slivers and stems byweight. Desirable flavoring materials also may be added at this point.The mixture is allowed to stand in tank 11 for about one hour or longerto impregnate the stem particles and slivers with water. Thereafter, thesoaked particles are discharged into a supply tank 12 which serves tofeed the particles to defibering device 13 referred to hereinafter ashomogenizer which separates the fibers making up the stems and sliverswithout breaking them up into materially shorter lengths. A suitablehomogenizer 13 is manufactured by Sonic Engineering Company of Stamford,Connecticut, and includes a screw-type or high pressure pump by means ofwhich the aqueous suspension of stem and sliver particles is forced athigh velocity through a conduit 14 shown in FIGURE 2, and through anozzle 15 having a slit 16 therein against the edge of a resilient blade17, somewhat similar to a razor blade which is mounted at its rear edgein a support 18 spanning a conduit 19. The aqueous suspension flowingthrough the nozzle 15 impinges on the edge of the blade 17 setting itinto high frequency vibration with the result that the particles aresubjected to impact and high intensity vibrations that separate the stemparticles and the slivers into their component fibers. By repeatedlyrecirculating the suspension through the nozzle by means of a bypassline 20 connected to the conduit and the supply tank 12 or by forcing itthrough a plurality of similar homogenizers connected in series, anaqueous suspension of tobacco fibers is produced. This material isdischarged into a mixing tank 21 where tobacco fines and No. 8s may beadded and mixed therewith in any suitable way, such as, for example,paddle-type or propeller-type mixers (not shown). The mixture at thisstage has an increased solids content and is considerably less fluid. Itis recirculated through another homogenizer 22 similar to homogenizer 13by means of a recirculating line 23 or through a series of homogenizers.When the tobacco fines have been disintegrated sufiiciently to form withthe fibers a semi-fluid slurry, it is delivered to a storage tank 24.

At this stage of the operation, the moisture content is about 6 to 8parts of water and one part of tobacco solids. Due to the thicksemi-fluid condition of the suspension, it is pumped by means of asuitable high pressure pump 25 or one or more booster pumps 26 to one ormore spray nozzles 27 which discharge the material downwardly through atower 28 onto an endless moving screen 29 similar to a paper-makingscreen thereby forming a thin layer L of wet tobacco particles on thescreen 29.

The upper surface of the layer L, due to the spray deposit of thetobacco fibers and particles, is somewhat rough. In order-to improve itssurface texture, the layer on the screen is passed below a smoothsurface sizing roller 30 which reduces the thickness of the layer L andsmoothes its upper surface. Inasmuch as the moist tobacco tends to clingto the surface of the roller 36, a suction box 31 actuated by vacuumpump 29 is positioned below the screen belt 29 to draw the tobacco awayfrom the roller 3t; and thus prevents sticking to the roller. Thesuction box 31 also removes about 50% of the water in the lawer L andthis liquid is returned from separator 30' to tank 11, with any tinytobacco particles that passed through the screen belt 29 remaining inseparator 30.

The screen belt 29 carries the particles forming layer L through adrying tunnel 32 which may be equipped with infrared heaters (notshown), or through which hot air may be circulated to reduce themoisture content of the tobacco layer L at the discharge end of thetunnel 32 to about 4 to 25% moisture, or to a point at which the layeror sheet L is self-sustaining and can be peeled as a continuous sheetfrom the surface of the screen belt 29. The lower degree of suchresidual moisture in the 4 to 25% range depends on whether or not thebelt 29 is pretreated with a non-sticking agent such as lecithin.

As illustrated in FIGURE 1, a recirculation line 33 having a reliefvalve 34 may be provided to return excess slurry from the pump 25 to thestorage tank 24.

In the operation described, no waste of tobacco products occurs. Anytobacco particles which are oversprayed in the tower 28, or sheetfragments which are produced when the production cycle is started, canbe returned to the mixing or supply tanks 11, 12 or 24 by respectivereturn lines 31', 20 or 28' and can be reprocessed and re-used.

In a typical example of the process, moistened tobacco stems and sliversare mixed with and soaked in about 12 parts of water for each part ofstems and slivers by Weight. The solid tobacco particles are allowed tosoak for at least one hour and then are delivered to the supply tank 12from which the water-tobacco suspension is discharged into thehomogenizer 13 and is recirculated therethrough about 10 to 12 timesuntil the stems and slivers are defibered and separated into thecomponent fibers. The resulting material is discharged into the mixingtank 21 where tobacco fines and No. 8 screen size particles are added.The tobacco fragments supplied to the system, in a typical operation,consist of about 60% stems and slivers, 20% factory by-products (tobaccofines) and 20% leaf fragments (No. 8s) by weight.

By adding the indicated proportion of fines and leaf fragments, theproportion of the solids to water in the suspension in the supply tank21 is about one part of solids to 8 parts of water by weight. This thickslurry is then homogenized or further defibered and subdivided bypassing it through the second homogenizer 22 about four to six times andis discharged into the storage tank 24 for supply by the pumps 25 and 26to the spray nozzle or nozzles 27. The material discharged through thespray nozzles 27 is an aqueous suspension having the ratio of solids towater indicated above.

The movement of the screen belt 29 is so related to the temperature inthe drying tunnel 32 that the issuing sheet L has at least 6% moisture.

The dried tobacco sheet L is light tan in color and has sufiicientstrength that it can be peeled readily from the belt 29 and can even befolded and creased sharply due to the presence of the matrix ofinterlaced fibers.

The process and the equipment for practicing it are susceptible toconsiderable modification. Thus, for example, additives such as flavors,humectants, wetting agents, and the like, may be introduced into thesoaking tank 11 With the water supplied thereto. Other types of highfrequency (supersonic) homogenizers or their equivalents may be used todisintegrate the stems and slivers into the component fibers. Moreover,instead of recirculating the suspensions and slurries through thehomogenizers l3 and 22, they may be forced successively through a seriesof homogenizers to obtain continuous production of the product.

While only one spray nozzle 27 is illustrated, it will be understoodthat a plurality of spray nozzles may be provided in the spray column 28when a sheet of substantial width is to be produced.

Drying of the sprayed layer can be accomplished in any number ofdifferent ways as, for example, by spraying the material on a continuousimperforate belt, or on a drying drum which may be heated in order toremove the moisture from the tobacco layer. The tobacco slurry may besprayed by a series of spray nozzles arranged along the length of a beltwith drying means interposed between the spray nozzles so that a firstthin layer is sprayed on the drying surface, partially dried; anotherlayer is sprayed on the partially dried layer and dried, and still otherlayers may be deposited and dried to build up the layer to a desiredthickness. Successive spraying and drying operations are especiallyuseful with an imperforate belt or a drum drier.

Inasmuch as tobacco dust is finely divided, it need not be added to thesuspension in the mixing tank 24 but may be handled separately. Thus,the mixture of stem and sliver fibers and finely-divided tobaccoby-products can be sprayed on a drying surface and the tobacco dust maybe then sprayed or sifted onto the wet layer prior to drying so that thefines will adhere to the layer. Likewise, the stems, the tobaccoby-products and fines may be homogenized separately and the slurry ofstems may be sprayed first to form a felt or mat onto which thefinelydivided by-products and the tobacco dust are sprayed.

While binders are not required for the production of a self-sustainingtobacco sheet, a very small proportion of binder may be added if. thesheet is to be subjected to extremely severe processing or handling.Thus, suflicient propylene glycol alginate can be added to the materialin any of the soaking or mixing tanks as may be desired, so that thefinished sheet will contain at least 1% of propylene glycol alginate.Also, as indicated above, humectants and flavoring materials can beadded in the usual ratio and they may be of any of the usual types.

Due to the low moisture content of the material undergoing treatment,drying of the sheet is greatly simplified and waste or loss of water inthe process is very substantially reduced as compared with priorprocesses. The less severe drying conditions and the lower content orcomplete absence of binders provides a tobacco sheet of a light brown ortan color similar to high quality cigarette tobacco which can beshredded and mixed in high proportion with other cigarette tobaccowithout altering the filling and burning properties, flavor or generalhandling characteristics of the tobacco.

From the foregoing description of the process and the specific examplethereof, it will be understood that the process is susceptible toconsiderable modification and, accordingly, the invention is not limitedsave by the terms of the following claims.

We claim:

1. A method of producing tobacco sheets from tobacco fragments includingstem material and tobacco fines comprising the steps of separating atleast partially the fibers of fiber bundles of said tobacco stemmaterial by disintegrating pieces of said tobacco stem material whilesuspended in a liquid without substantial reduction of the length ofsaid fibers to form a thick semi-fluid mixture thereof, spraying saidmixture and said tobacco fines onto a surface to form a layer of saidfibers and fines thereon, and drying said layer to form aself-sustaining sheet in which said fibers are interlaced to impartstrength to said sheet.

2. The method set forth in claim 1 in which said tobacco fines arepresent in said fluid mixture and are sprayed with said fibers onto saidsurface.

3. The method set forth in claim 1 in which said slurry and said tobaccofines are sprayed successively onto said surface.

4. A method of producing tobacco sheets from tobacco fragments,comprising forming a mixture of about one part of tobacco stem piecesand about 6 to 13 pants of water, subjecting said mixture to highfrequency vibrations to separate, at least partially, the fibers of thefiber bundles of the tobacco stem pieces Without substantial reductionof their length which fibers interlace and form a self-sustainingmatrix, adding tobacco fines in a finelydivided state to said mixture,spraying said mixture onto a surface to form a layer thereon containingsaid fibers in an interlaced condition and forming a matrix containingsaid finely-divided particles, and heating said layer to evaporatemoisture from said layer to form a self-sustaining sheet.

5. A method set forth in claim 4 comprising subjecting said mixture ofstem fibers and tobacco fines to high frequency vibrations and agitationto mix them thoroughly and reduce the size of said fines.

6. The method set forth in claim 4 in which said surface is porous andsaid layer and surface are subjected to pressure and suction to compressand partially dry said layer.

7. The method set forth in claim 4 in which said mixture is a thickslurry containing about one part of fibers and particles by weight andabout 6 and 8 parts by weight of water.

8. A method of making tobacco sheets from tobacco fragments comprisingpassing a rapidly flowing mass of tobacco stern fragments into contactwith a thin blade vibrating at supersonic frequency and leaf fragmentsto disintegrate said fragments and form an aqueous slurry of fineparticles of leaf tobacco and stem fibers of substantial length capableof matting together to form a selfsustaining matrix, when dry, saidslurry containing about one part of stem fibers and leaf particles toabout 6 to 8 parts of water by weight, spraying said slurry onto asurface to form a thin layer of interlaced stem fibers and leafparticles thereon, rolling said layer and subjecting it to suction toreduce the layer to a predetermined thickness and to remove watertherefrom with the resulting liquid returned for reuse, and drying thelayer to form a selfsupporting sheet.

9. The method set forth in claim 8 in which said stem fragments are atleast partially disintegrated into stem fibers prior to mixing them withtobacco particles.

10. A method of making sheet tobacco from tobacco fragments, comprisingbreaking tobacco stems and tobacco slivers into pieces not exceedingabout one-half inch long, soaking the pieces in Water in the proportionof about one part of the pieces to between about 6 and 13 parts ofwater, by weight, to form an initial thick slurry, subjecting saidslurry to abrasion and impact at supersonic frequency to at leastpartially separate the fibers of said pieces, adding leaf fragments tothe slurry to reduce the ratio of solids to liquid to between about 1 to6 and 1 to 8 by weight, subjecting the slurry to abrasion and impact atsupersonic frequency to further separate the fibers of said stems andslivers and reduce the leaf fragments to a finely-divided state,spraying said slurry onto a surface to form a thin layer of interlacedfibers and leaf particles intermingled with said fibers, and drying saidlayer.

11. The method set forth in claim 10 in which said layer is partiallydried by subjecting it to suction to withdraw water, the water isreturned for admixture with said tobacco fragments, and said layer isheated to evaporate water therefrom.

12. The method set forth in claim 6 in which the liquid removed fromsaid layer is returned to said initial mixture of tobacco stem piecesand water.

13. The method set forth in claim 8 in which the water removed from saidlayer by rolling and suction is returned to said aqueous slurry.

14. The method set forth in claim 11 in which the water withdrawn bysuction from said layer is returned to said initial slurry of tobaccoand water.

References Cited in the file of this patent UNITED STATES PATENTS 86,368Consuegra et al. Feb. 2, 1869 267,784 Wood Nov. 21, 1882 346,887 BennettAug. 10, 1886 1,907,046 Darrah May 2, 1933 2,034,784 Wallny Mar. 24,1936 2,265,455 Serpas Dec. 9, 1941 2,377,252 Lehrecke May 29, 19452,433,877 Wells et al. Jan. 6, 1948 2,584,053 Seavey Jan. 29, 19523,020,179 Hess Feb. 6, 1962 3,043,723 Cleverdon July 10, 1962 FOREIGNPATENTS 229,817 Australia Aug. 9, 1960 988,509 France May 9, 1951570,265 Great Britain June 29, 1945 796,932 Great Britain June 25, 1958UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION July 21 1964Patent N00 3 14l 462 M Sabel Block et all,

It is hereby certifiedv that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column l line 33 for "unit" read unite column 6 line 55 for "26%784"read 267 764 Signed and sealed this 24th day of November 1964,

(SEAL) Attest:

EDWARD J. BRENNER I ERNEST W SWIDER' Commissioner of Patents AttestingOfficer

4. A METHOD OF PRODUCING TOBACCO SHEETS FROM TOBACCO FRAGMENTS,COMPRISING FORMING A MIXTURE OF ABOUT ONE PART OF TOBACCO STEM PIECESAND ABOUT 6 TO 13 PARTS OF WATER, SUBJECTING SAID MIXTURE TO HIGHFREQUENCY VIBRATIONS TO SEPARATE, AT LEAST PARTIALLY, THE FIBERS OF THEFIBER BUNDLES OF THE TOBACCO STEM PIECES WITHOUT SUBSTANTIAL REDUCTIONOF THEIR LENGTH WHICH FIBERS INTERLACE AND FORM A SELF-SUSTAININGMATRIX, ADDING TOBACCO FINES IN A FINELYDIVIDED STATE TO SAID MIXTURE,SPRAYING SAID MIXTURE ONTO A SURFACE TO FORM A LAYER THEREON CONTAININGSAID FIBERS IN AN INTERLACED CONDITION AND FORMING A MATRIX CONTAININGSAID FINELY-DIVIDED PARTICLES, AND HEATING SAID LAYER TO EVAPORATEMOISTURE FROM SAID LAYER TO FORM A SELF-SUSTAINING SHEET.